Spinning solution containing an aluminum complex



grates 3,fi38,730 Patented June 12, 1962 3,038,780 SPINNING SOLUTION CONTAINING AN ALUMINUM COMPLEX John E. Kiefer and George P. Touey, Kingsport, Tenn, assignors to Eastman Kodak Company, Rochester,

N.Y., a corporation of New Jersey No Drawing. Filed Oct. 23, 1959, Ser. No. 848,188 5 Claims. (Cl. 18-54) This invention concerns a new spinning solution and the process of spinning such solution into fine denier filaments. More particularly, this invention concerns the incorporation of relatively small amounts of certain aluminum compounds into cellulose acetate spinning solutions whereby the viscosity of the cellulose acetate solution is increased in a manner that facilitates the spinning of fine denier filaments therefrom.

In our companion application Serial No. 848,187 we have described that in the production of cellulose acetate yarn, cellulose acetate is dissolved in acetone or the like solvent. The spinning dope is put under pressure and forced through small holes or orifices in a spinneret. The .fine strands of dope are continuously pulled from the spinneret through a spinning cabinet where the solvent is evaporated by means of hot air. The denier of the resulting filaments can be defined by the factors of dope solids, draft, dope density, and orifice diameter as follows:

K (dope percent solids) (orifice diameter) (dope density) The spinning draft is defined as the linear speed of yarn take-up divided by the linear extrusion speed of the spinning solution at the orifice. In many instances spinning draft is limited to about 1.8. Excessive draft can result in many broken filaments and filaments with reduced physical properties.

The above relationship suggests changing the orifice diameter as a means of varying the denier of cellulose acetate filaments. However, when spinnerets with orifices with diameters less than about 0.035 mm. are used, mechanical difficulties may arise in the spinning operation. The acetate spinning dope does not flow through the smaller holes at an even rate and the holes tend to become clogged.

' The denier of cellulose acetate filaments can also be varied by varying the solids content of the spinning dope. It is apparent that lowering the solids concentration of a dope will decrease the denier of the resulting filament, assuming the extrusion rate and the take-up rate are held constant. However, when the solids content of cellulose acetate is decreased, the dope viscosity also decreases. This produces difficulties in controlling the proper flow rate of the dope through he spinneret. Also, dopes with low viscosity may tend to stick to the metal spinneret and are, therefore, difficult to pull into filaments. One method of eliminating this problem is to use a cellulose acetate with a higher intrinsic viscosity than is normally used for cellulose acetate yarn. The higher cost of producing a high intrinsic viscosity ester has tended to make this approach unattractive.

' In recent years there has developed a market for fine denier filaments. One particular use therefor is the manufacture of tobacco smoke filters from such fine denier cellulose acetate filaments. It is apparent, therefore, that the development of simple, less expensive procedure for making such cellulose acetate filaments represents a highly desirable result.

After extensive investigation we have discovered a relatively simple way by which such fine denier filaments may be produced without involving the change of presently used spinning equipment or other material changes in existing processes for producing cellulose acetate filaments.

This invention has for one object to provide a cellulose acetate spinning solution of increased viscosity but with relatively low solids content. Still another object is to provide a way of improving cellulose acetate spinning solutions whereby they may be more readily spun into fine denier filaments. A particular object is to provide a cellulose acetate spinning solution which has a relatively small amount of certain aluminum compounds therein. Still a further object is to provide a method for spinning cellulose acetate filaments of relatively small deniers such as deniers of the order of 0.2-2 denier per filament. Other objects will appear hereinafter.

In the broader aspects of our invention we have now found that commercial yarn grade cellulose acetate spinning dope diluted with acetone to a low solids content (15-23% which concentration is not normally suitable "for spinning, can be made suitable for spinning by the addition of 0.1 to 1.0% by weight (based on the cellulose acetate content) of aluminum chelate esters. The aluminum compounds apparently affect the cellulose acetate in a manner which results in a large increase in the viscosity of the cellulose acetate spinning dope. The large increase in dope viscosity on addition of small amounts of aluminum chelates was unexpected.

Therefore, the present invention is accomplished by adding 0.01 to 1.00% (by weight of the cellulose acetate) of an aluminum chelate to a low solids cellulose acetate spinning dope, then spinning the dope into yarn using conventional cellulose acetate spinning equipment.

The aluminum chelates useful in carrying out this invention are those chelates which are soluble in the dope solvent, are fairly resistant to hydrolysis (most cellulose acetate spinning dopes contain some water) and which react with the free hydroxyl groups of the cellulose acetate. They have the following composition:

where x=0, 1 or 2 and R represents an alkyl or aryl hydrocarbon such as the ethyl, propyl, butyl, Z-ethylhexyl or phenyl group. R represents an oxy compound capable of chelating with aluminum such as dihydroxy, diketo, hydroxy keto compounds, hydroxy carboxylic acids and their esters and keto carboxylic acids and their esters. Examples of the oXy chelating compounds useful in carrying out this invention are acetyl acetone, ethyl acetoacetate, di-acetone alcohol, '1,3-octylene glycol and ethyl lactate.

The cellulose acetate which can be used in carrying out this invention is preferably of yarn grade acetone soluble cellulose acetate with an acetyl content of 37 to 42%.

The cellulose acetate spinning dopes which can be used in carrying out this invention consist of 10-23% cellulose acetate, 76 to 89% acetone, 0.5 to 3% water and 0.01 to 0.50% of the aluminum chelate.

A further understanding of our invention will be apparent from the several examples which follow for illustrating certain of our preferred embodiments.

EXAMPLE I A cellulose acetate dope was prepared consisting of 20% cellulose acetate and 80% acetone. The dope was divided into 1 kg. samples. One sample was used as a control. An aluminum compound in accordance with the present invention was added to the other samples. Each dope was then mixed 30 minutes. The viscosity of the dopes was measured with a Brookfield viscometer. The dopes were stored at room temperature and the viscosity was redetermined at intervals. The results shown on Table I which follows illustrate how aluminum com- 3 plexes affected the viscosities of these dopes. The data indicates that the aluminum compound increases the viscosity of the cellulose acetate very rapidly. Following this initial increase of viscosity, no further change in the dope is apparent.

EXAMPLE II A cellulose acetate spinning dope consisting of 20% cellulose acetate, 78% acetone and 2% water was divided into two portions. One portion was spun using a conventional cellulose acetate spinning cabinet. A spinneret with orifices with 0.0 35 mm. diameter was used. The spinning draft was maintained at 1.5. The dope stuck to the face of the spinneret, stopping up the orifices. N yarn with satisfactory tensile properties could be obtained.

Acetyl acetone aluminate (0.5% based on the cellulose acetate weight) was added to the second portion of the dope. On mixing, the viscosity of the dope increased from 8,000 cps. to 31,200. This dope was spun into yarn using a conventional cellulose acetate spinning cabinet. A spinneret with orifices with a 0.035 mm. diameter was used. The 0.93 denier per filament yarn obtained had a tensile strength of 1.41 grams per denier and an elongation of 26%.

EXAMPLE III A cellulose acetate spinning dope consisting of 18% cellulose acetate, 80% acetone and 2% water had a viscosity of 4,700 cps. The dope could not be spun into yarn using conventional techniques. Seven-tenths percent ethyl acetoacetate aluminate was added to the dope. The viscosity increased to 34,500 cps. The dope was then spun into yarn using a conventional spinning cabinet. A spinneret with 0.035 mm. orifices and a spinning draft of 1.5 was used. Sixty-two hundredths denier per filament yarn was obtained. It had a tensile strength of 1.34 grams per denier and an elongation of 29%.

Table I Viscosity of Dupes, Ops. Aluminum Complex, 0.5% Gone. based on the Cellulose Acetate After 30 1 Day 30 Days Min.

No additive (control) 8, 000 8, 100 8, 300

Ethyl acetoacetate aluminate (Harshaw Chem. Co. PEA-1)-.-- 35, 800 35,700 35, 900 Acetyl acetone aluminate. 31, 200 31,200 31, 400 Diacetone alcohol alumina 37, 500 37, 600 37, 300 Octylene glycol aluminate 29, 300 30,100 30, 000

The aluminum additive materials used in this invention in the relatively small amounts of .021.5% may in many instances be obtained commercially. In certain cases the compounds may be prepared by relatively simple esterific-ation methods if it is desired to prepare such compounds rather than purchase them. For example, the ethyl acetoacetate aluminate referred to above is a compound having the general formula:

031170 OC3H7 All While We prefer to operate with acetone solutions of cellulose acetate, since as is well known, acetone is the common readily available commercial solvent frequently used for dissolving cellulose acetate, our invention will function when other solvents are used for the cellulose acetate. Accordingly, our invention is not limited to the particular cellulose acetate acetone solutions described above.

Fine denier filaments produced in accordance with this invention have utility for various purposes such as in the production of cigarette filters or for making cellulose acetate fabrics with an extremely soft, silky feel. This type of feel is designated by the trade as a fine hand. An illustration of a cigarette filter prepared from fine denier filaments produced by the present invention is as follows:

Twenty thousand filaments of 0.62 denier per filament cellulose acetate yarn were pulled together to form a tow. This tow was then crimped to 20 crimps per inch. The crimped tow was spread out to a width of two feet and sprayed with glycerol triacetate plasticizer until its weight had increased by 14%. It was then compacted again into the form of a cord and processed into filter rods on a standard cigarette filter rod making machine. The rods which had a circumference of 25.5 mm. were cut into 15 mm. lengths and attached to a domestic brand of cigarettes. These cigarettes were smoked on an automatic standard cigarette smoking machine. The smoke was collected and analyzed for its nicotine and tar content. Fifty-six percent less tars and nicotine were obtained from these filtered cigarettes than were obtained from the same brand of cigarettes without a filter.

The aluminum complex addition to the spinning solutions of the present invention appear to function in a manner similar to the functioning of the titanium additions of our companion copending application referred to above. However, we do not regard the aluminum complexes the equivalent of the titanium and, therefore, prefer in many instances to utilize the procedure set forth in said companion application. Nevertheless, the aluminum complexes of the present invention are quite satisfactory and in instances such as when the dopes contain abnormal amounts of water, certain aluminum complexes are preferred.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

1. A spinning solution consisting essentially of cellulose acetate, solvent therefore and an amount of aluminum chelate compound of 0.02 to 1.5% based on the weight of the cellulose acetate, said chelate compound having the properties of dissolving in said solvent, causing a substantial increase in the viscosity of the spinning solution, being fairly resistantsto hydrolysis and falling under the empirical formula:

wherein x represents a figure from the group consisting of 0, 1 and 2, R represents a group from the class consisting of ethyl, propyl, butyl, 2-ethylhexyl and phenyl and R represents an oxy-compound capable of chelating with aluminum from the group consisting of dihydroxy, diketo, hydroxy keto, hydroxy carboxylic acids and their esters and keto carboxylic acids and their esters.

2. The method for producing an improved cellulose acetate spinning solution which comprises adding 0.02 to 1.5%, based on the Weight of the cellulose acetate, of an aluminum material chelated with a material from the group consisting of octylene glycol, ethyl acetoacetate, diacetone alcohol and ethyl lactate, to a solution which contains as essential ingredients cellulose acetate and acetone.

3. The method of making fine denier filaments which comprises forming a spinning solution containing cellulose acetate 15-23%, 0.02 to 1.5% based on the weight of the cellulose acetate of an aluminum chelate having the properties of dissolving in the spinning solution solvent, causing an increase in viscosity of the spinning solution as well as being resistant to hydrolysis and wherein the aluminum chelate consists of aluminum chelated with a material from the group consisting of octylene glycol, ethyl acetoacetate, diacetone alcohol and ethyl lactate.

4. The method in accordance with claim 3 wherein the solution is forced through spinneret holes of a diame ter not substantially greater than 0.035 mm. and with- 6 drawing the filaments formed at a draft not greater than about 1.8 and into an atmosphere which evaporates the solvent. 5. The method in accordance with claim 3 wherein the viscosity of the spinning solution is between 15,000 and 70,000 cps.

References Cited in the file of this patent UNITED STATES PATENTS 10 2,072,102 Dreyfus Mar. 2, 1937 2,680,108 Schmidt June 1, 1954 2,916,777 Crane et a1 Dec. 15, 1956 2,933,475 Hoover et a1. Apr. 19, 1960 

3. THE METHOD OF MAKING FINE DENIER FILAMENTS WHCIH COMPRISES FORMING A SPINNING SOLUTION CONTAINING CELLULOSE ACETATE 15-23%, 0.02 TO 1.5% BASED ON THE WEIGHT OF THE CELLULOSE ACETATE OF AN ALUMINUM CHELATE HAVING THE PROPERTIES OF DISSOLVING IN THE SPINNING SOLUTION SOLVENT, CAUSING AN INCREASE IN VISCOSITY OF THE SPINNING SOLUTION AS WELL AS BEING RESISTANT TO HYDROLYSIS AND WHEREIN THE ALUMINUM CHELATE CONSISTS OF ALUMINUM CHELATED WITH A MATERIAL FROM THE GROUP CONSISTING OF OCTYLENE GLYCOL, ETHYL ACETOACETATE, DIACETONE ALCOHOL AND ETHYL LACTATE.
 4. THE METHOD IN ACCORDANCE WITH CLAIM 3 WHEREIN THE SOLUTION IS FORCED THROUGH SPINNERET HOLES OF A DIAMETER NOT SUBSTANTIALLY GREATER THAN 0.035 MM. AND WITHDRAWING THE FILAMENTS FORMED AT A DRAFT NOT GREATER THAN ABOUT 1.8 AND INTO AN ATMOSPHERE WHICH EVAPORATES THE SOLVENT. 